Works great for shopping, but unfortunately catches AWS websites as well as Amazon Commerce, so it breaks getting to console.aws.amazon.com. A feature to disable for *.aws.amazon.* would help greatly. I had to disable it.

Developer response

Works well, one small issue is that if you click a direct product link (non-smile) while not logged in, it goes into a redirect loop until you open a new tab, go to Amazon Smile, and login. Doing that then allows the tab to load.

Before today I would have said this was no longer working and hasn't been for some time. Today I removed the add-on, restarted and re-installed, and it started working. I'm happy again. I'm using Firefox 63.0.3.